Primary seal for floating tank roof



Oct. 8, 1963 w L. F. SCHERER 3,106,310

PRIMARY SEAL FOR FLOATING TANK ROOF Filed Oct. 7, 1960 Til .1.

United States Patent Texas Filed Oct. 7, 1960, Ser. No. 61,261 1 Claim. (Cl. 220-26) This invention relates generally to a floating tank roof and specifically to a sealing means for the space between the floating tank roof and the inner surface of the tank shell or wall. Tanks with floating roofs for the storage of fluids, such as volatile liquids require means for sealing the annular area between the edge of the floating roof and the tank shell. The sealing means prevents the escape of vapors from volatile liquids contained therein and prevents contamination from water, dirt and the like from the exterior; In addition, there is the problem of sealing as the floating roof rises and falls as the height of the liquid contained within the tank varies.

Considerable difiiculties have arisen with the use of primary seals of sheet metal as used with the floating tank roofs. With such use of a primary seal, a complicated hanger construction is required. It appears that many troubles would be eliminated and better sealing could be obtained by removing the entire primary seal structure together with the hanger construction and adapting a single rain seal for use as a primary seal.

relatively simple primary seal which can be used and replaced without much difficulty.

These and other objects, features and advantages of the invention will become apparent by reference to the specification and claim and the drawing attached herewith wherein:

FIG. 1 is a partial perspective sectional view of tank structure disclosing the manner in which the novel primary seal is attached to a floating roof; and

FIG. 2 is a partial perspective cross sectional vie of the primary seal.

In the drawing, there is disclosed a partial cross section view of a storage tank having a floating roof, showing the upper part of the tank comprising the side wall 11 with a wind-girder at 1=1a, a floating pontoon type roof at 12 having upper and lower decks 13a and 13b respectively, and peripheral rim wall at 14 which is shown as extending past the top deck and ending in an inwardly extending flange 14a to which is attached a circular plate 15, which may be bolted or aflixed in some other manner. This circular plate extends outwardly from the floating roof to provide a partial closure of the annular space between the floating roof and the side wall 11 and is flat except for the outer edge which is defined by an upwardly extending flange 15a and could be angled as shown or may be at right angle to the remainder of the plate 15.

The primary or combination rain and gas seal comprises the tapered flexible member or wiper 20, of resilient material, disclosed in coassigned and copending application for patent by Messrs. Nelson and Bagwell, Serial No. 61,260, for a Secondary Seal for Floating Tank Roof, and consists of an elongated tapered surface contacting portion at 21 and an enlarged support portion having an offset at the wider end of the seal as indicated at 22. The offset portion is defined by a curved surface at 22a and two flat surfaces 23a and 23b extending from the curved surface 22a and from the surface contacting face respectively to intersect at a right angle, with a notch 2.4 extending inwardly from the projected intersection of the flat faces. The axis of this notch 24 and the longitudinal axis of the elongated tapered portion intersect at an obtuse angle 25, so that when member 20 is positioned on flange 15a, there will be a wide surface in sealing contact with the side wall 11. Further, the dimensions of the surface contacting portion of the primary seal are such that the seal will operate despite the wall irregularities of large diameter tanks and will remain in contact with the side Wall of the tank to prevent ingress of contaminants and egress of vapors. With the elimination. of the sealing shoes and hanger construction, other centering and spacing devices for the floating roof would be provided, e.g. wheels (not shown).

Prior art floating tank roof seals have the problem of preventing the entry of contaminants when the seal is forced to assume a position so as to form a pocket between the tank wall and the seal itself. The primary seal 20 is designed to have free sliding contact with the inner Wall surface of the tank and to be free of pockets to collect water and the like. Obviously, when used as a primary seal, member 20 would be heavier in section and considerably stiffer than when used as a secondary seal as disclosed in the above cited copending application. And, as disclosed therein, the primary seal is attached to the edge 15a in the same manner, viz. by adhesive, after the edge has been cleaned. With the present structure, there is no difliculty when the floating roof moves downward as the liquid storage level is reduced, and when the floating roof rises, there is sufficient scraping action between the tank wall and the combination rain and gas seal that foreign material is removed and so prevented from entering the tank.

Thus, it can be seen that a simple primary seal for a floating roof is provided without complicated prior art primary seals and hanger structures.

I claim:

In combination, an open end fluid storage tank having an upstanding wall, a floating roof for said tank centered therein and spaced annularly from said wall, and means for covering the annular area between said roof and said wall comprising a substantially horizontal, outwardly extending, rigid, metallic flange with an upwardly angled outer edge projecting from said roof toward said wall and replaceable, non-metallic, sealing means fastened to said outer edge of said metallic flange and contacting said wall, said sealing means being resilient and formed with a surface contacting portion and an offset support portion angularly disposed thereto with the axes of these portions intersecting at an obtuse angle facing said wall, whereby, when said sealing means is positioned operatively, wide surface contact with said wall is assured and entrance of contaminants is prevented as said roof rises and falls with changes in the fluid storage volume in said tank, said surface contacting portion being elongated and outwardly thinned for contact with said wall, said offset support portion being thickened for support on the flange edge and having a' slot at its outer end centered on the 7 axis of said support portion with dimensions for a tight fit on said upwardlyangled outer edge of said metallic flange.

References Cited in the file of this patent UNITED STATES PATENTS Fino Feb. 28, 196 

